1. Field of the Invention
The present invention relates to a recording/reproducing apparatus, and, more particularly, to an optical disk apparatus which optically records data on tracks of an optical disk, or reads recorded data therefrom by rotating the optical disk in relation to an optical head.
2. Description of the Related Art
Image filing systems use an optical disk apparatus, which records data on spiral or concentric tracks formed on an optical disk o reproduces recorded data therefrom while rotating the optical disk.
An original is two-dimensionally scanned so that its image data is photoelectrically converted into electric image data. The electric image data is optically recorded on the tracks of the optical disk by an optical head. The recorded data is retrieved by the optical head at the time of retrieval and is reproduced as a hard copy or a soft copy.
The optical disk apparatus performs data writing or data reading with a laser beam produced by a semiconductor laser oscillator provided in the optical head. In such an optical disk apparatus, the specifications of usable optical disks, such as the reflection factor, the laser powers required for data writing and data reading, and the number of sectors around the optical disk, are fixed.
There is a demand and movement to permit the use of optical disks with different specifications which are manufactured by various companies. If optical disks have different specifications mentioned above, they cannot generally be used in a single optical disk apparatus.
As a solution to this shortcoming, there is proposed an optical disk on which specifications data such as mode data different for each manufacturer, or a so-called control track, is recorded for standardization. This control track is recorded in a specifications data recording area for specifications data, which is located inward of a data recording area where record data is to be recorded. Data of the specifications indicating the manufacturer of this optical disk is recorded in bar code on this control track. Each bar of the bar code consists of a group of pits arranged in rows and columns.
Also recorded on the control track is data, such as the reflection factor, the laser powers required for data writing and data reading, and the number of sectors around the optical disk, in order to determine the reading/writing specifications.
In this case, there are two types of optical disks: rewritable optical disks which require a high-power laser beam for data reading and write-once type optical disks which require a low-power laser beam for data reading. When a high-power laser beam is erroneously irradiated on the write-one optical disk to access the control track, the data on the optical disk would likely be destroyed.